Fluid Management for Hypernatremia in Children
For treating hypernatremia in children, use 5% dextrose in water (D5W) as the primary intravenous fluid, and strictly avoid normal saline (0.9% NaCl) which will worsen hypernatremia. 1, 2
Primary Fluid Recommendation
The fluid of choice is 5% dextrose in water (D5W) because it delivers no renal osmotic load and allows for gradual correction of hypernatremia. 1
- Salt-containing solutions, especially 0.9% NaCl, must be avoided because their tonicity (
300 mOsm/kg H2O) exceeds typical urine osmolality in conditions causing hypernatremia (100 mOsm/kg H2O) by approximately 3-fold 1 - When 1 liter of isotonic saline is given, approximately 3 liters of urine are needed to excrete the renal osmotic load, which risks worsening hypernatremia 1
- The American Academy of Critical Care Medicine explicitly recommends avoiding normal saline in hypernatremia with hyperchloremia, as it contains 154 mEq/L of sodium and would worsen both abnormalities 2
Initial Fluid Rate Calculation
Calculate the initial infusion rate based on physiological maintenance requirements using the Holliday-Segar formula: 1
- First 10 kg: 100 ml/kg/24 hours
- 10-20 kg: Add 50 ml/kg/24 hours for each kg above 10 kg
- Above 20 kg: Add 20 ml/kg/24 hours for each kg above 20 kg (in children; 25-30 ml/kg/24 hours in adults)
This maintenance rate with D5W will result in a slow, controlled decrease in plasma osmolality 1
Alternative Fluid Options
If some sodium replacement is needed (rare in pure hypernatremia), half-normal saline (0.45% NaCl) can be considered, but only after careful assessment. 2
- Half-normal saline provides less sodium (77 mEq/L) and chloride than normal saline 2
- This option should only be used when there is concurrent volume depletion requiring some sodium replacement 2
For oral rehydration when feasible, glucose-electrolyte solutions containing 75-90 mEq/L sodium can be used slowly. 3
- Oral rehydration solutions administered slowly (over 14-17 hours) have been shown safe and effective in hypernatremic dehydration 3
- The slow administration allows gradual correction without rapid sodium shifts 3
Critical Monitoring Parameters
Check serum sodium every 2-4 hours initially to ensure appropriate correction rate. 2, 4
- The rate of sodium decline should not exceed 0.5-1 mEq/L/hour or 10-12 mEq/L per 24 hours to avoid cerebral edema 4, 5
- For chronic hypernatremia (>48 hours), correction should not exceed 8-10 mmol/L/day to prevent osmotic demyelination 5
- A median decline rate of 0.65 mEq/L/hour has been shown safe in pediatric studies 4
Special Clinical Considerations
Patients with impaired renal function, heart failure, cirrhosis, or significant renal concentrating defects require closer monitoring and may need modified fluid management. 2
- These patients have impaired ability to excrete sodium and free water 2
- Even isotonic fluids could worsen hypernatremia in patients with significant renal concentrating defects 2
- Patients with ongoing free water losses (voluminous diarrhea, severe burns) may require adjustment of therapy 2
Common Pitfalls to Avoid
The most dangerous error is using normal saline for hypernatremia correction, which paradoxically worsens the condition. 1, 2
- Normal saline has a higher sodium concentration (154 mEq/L) than the patient's serum in most hypernatremic cases 1, 2
- The high osmotic load requires excessive urine output to excrete, leading to further free water loss 1
Correcting hypernatremia too rapidly can cause cerebral edema and seizures, particularly in chronic hypernatremia. 6, 5
- Rapid correction allows water to shift into brain cells faster than they can eliminate accumulated osmoles 6
- This is especially dangerous in infants and young children who are more vulnerable to neurological complications 6, 7
Failure to provide adequate free water in patients with restricted access to fluids and ongoing losses leads to progressive hypernatremia. 6